1. Field of the Invention
This invention relates to an imaging system, an electronic camera, a computer system for controlling the electronic camera, and a method of controlling these systems as well as the electronic camera.
2. Description of the Related Art
Electronic cameras for photographing a subject and outputting an analog video signal or digital image signal which represents the image of the photographed subject include video cameras, still-video cameras (electronic still-video cameras), digital still-video cameras (digital electronic still-video cameras), etc.
Without exception, these electronic cameras are such that shutter release, as a matter of course, and the setting (with the exception of cases in which automatic setting is performed) of so-called camera control parameters for image pick-up and image processing, such as amount of exposure (f-stop and shutter speed) and white balance, are carried out on the side of the electronic camera using switches, buttons, etc., provided on the electronic camera.
Electronic cameras, especially digital-type electronic cameras in which digital image data is obtained, have recently become the focus of much attention since they make possible the development of applications that can be used in tandem with a computer system. For example, new media can be created by preserving image data, which represents the image of the subject obtained from the electronic camera, on a recording medium such as an optical disk or magnetic disk provided in a computer system, and editing the image data. This new media can be utilized in the presentation of official reports, advertisements and data, as well as in the provision of information, using visual images.
In order to create such new media, the image data obtained by photography using the electronic camera must be transmitted to the computer system. Since the image data generally is of great volume, transmission requires a long period of time.
Before the image data representing the image of the subject photographed by the electronic camera is stored on the recording medium, determining whether the subject has been photographed properly is important. If photography is improper, it is required that photography, inclusive of resetting of the camera control parameters, be performed again.
In order to visually determine whether the subject has been photographed properly, it is required that the image of the subject represented by the digital image data obtained from the electronic camera be displayed on a display unit. When it is attempted to display the image of the subject on the screen of a display unit provided in the computer system, it is necessary for all of the image data to be transmitted from the electronic camera to the computer system. As a result, the transmission time is prolonged, as mentioned above, and efficiency declines.
The setting of the camera control parameters for photography is carried out in the electronic camera, as mentioned above. Whenever the photographic conditions are changed, the operator of the computer system is compelled to go to the location of the electronic camera to make the necessary adjustments. This is a troublesome task.
Furthermore, it is not necessarily desirable for the entirety of the image of the subject photographed by the electronic camera to be always stored on the recording medium. There are cases in which only part of the photographed image of the subject is required. If only the necessary image data is cut out and stored on the recording medium, the volume of data is reduced. In addition, the image stored on the recording medium is required to be enlarged or reduced as needed.
In an imaging system configured by linking an electronic camera and a computer system in view of the foregoing points, it is preferred that the imaging system be so arranged that such operations as the operation for performing photography, the operation for communicating the image data and the operation for storing the image data on the recording medium all be implementable on the side of the computer system.
A solid-state electronic image sensing device such as a CCD has the advantage of being small in size and therefore is utilized in electronic still-video cameras and the like. However, a solid-state electronic image sensing device may produce an output of a spurious signal indicative of smear or the like, and flicker may occur owing to a difference in the magnitude of dark current caused by a difference in field read-out time. Consequently, in a case where the solid-state electronic image sensing device is utilized in an electronic still-video camera, it is necessary to prevent output of the spurious signal and to perform photographic processing through which the dark currents are made to coincide every field.
Conventional photographic processing operations for sweeping out smear charge and making the magnitudes of dark current coincide are controlled separately by an imaging processor contained in the electronic still-video camera. Consequently, a problem which arises is that there is an increase in the number of control lines in the electronic still-video camera, which are provided in addition to those for recording. It is vital that this problem be solved, especially in an electronic still-video camera having a separable camera head.